When calculating extract recipes, efficiency is applied only to the grains in the recipe and not to the extracts or sugars. If the recipe is strictly extracts, then efficiency is ignored. In this case, perhaps an efficiency in the range suggested by Promash would work; or perhaps not. Ultimately, the measured original gravity is the true test.

If you are doing a partial mash, efficiency should be treated just the same as with a full mash. Again, the extract portion of the recipe is calculated independent of the efficiency. The default efficiency is just a ballpark number; your technique, equipment, and ingredients all influence efficiency. Use an efficiency that best matches your process.

Hello. Trying to develop my own techniques for partial mash and here is what I have so far after 3 partial mashes regarding efficiency.

I have an igloo cooler tun, 2 gal with a 1/4" copper manifold. Works great. I have done three batches so far. 1st one, didn't really know about efficiency calculations.
2nd one I read Palmer's book and used his calculations to determine efficiency.
1. Measure the gravity of your collected partial mash wort. Drop the 1.0
2. multiply times gallons of collected partial mash wort
3. Divide that by lbs grain used
Palmer says this number should be better than 25.
4. Divide that by maximum yield spec for specific grain for efficency percent

so I realized that I was getting crappy efficiency, but I read chris colby's article on stove-top partial mash and he says partial mash's won't garner as high an efficiency. But I still thought it was way low. Makes me think Promash 30% is more correct but 30% why bother wasting the grain.

so I read a little about raking the grain and slower sparging and here was my third batch brewing an alt

I guess my point was that I need to do this a couple of more times to get a feel for how my own system works. As jeff states above, kind of.

My next step in understanding is getting the mash pH correct. I read a paper by Ken Scwartz on Coverting all-grain recipes to Partial-mash. Really interesting. In that paper he says that the easiest way to get mash pH correct is simply use distilled water and 1 tablespoon of DME per gallon of water. It worked great on my 2nd mash as shown above, mash was 5.3 right in line. But when i did my alt the pH was 4.9 alittle low so I was scrambling to raise it using calcium carbonate. I hated this part because I felt so unorganized. I wasn't sure how much to add in and futzing with the tun dropped my temp. i am assuming that the darker grains (Carafa III) dropped the pH. Does that sound right? How about some advice?

You're probably underestimating your efficiency a bit because your target gravity is so high. Pilsner, Munich, Wheat & Aromatic probably have a potential closer to 34 points per pound, while Carafa III is probably about 28.

The pH is determined by roast color and water. Read Palmer's advice on setting Residual Alkalinity based on target SRM, if you want to try fine tuning your water.

Remember, thet crush size and sparge volume are the biggest influences on mash efficiency. The finest crush that doesn't give you a stuck mash will give you the highest efficiency, as will the largest sparge volume that doesn't drop you below 1.010 (or you'll get astringency). You can use 2 sparges to increase sparge volume if batch sparging.

Also, be sure your hydrometer is accurate and that you are adjusting for temperature.

Higher volume increases efficiency because you get more volume at a lower gravity, but the total extracted points (volume x gravity) is higher.

Think of it this way, if you've sparged and got 2.5 gallons, then sparged with an additional 0.5 gallons, the gravity of that extra runnoff would be lower gravity than the earlier runoff, but would still add to the total extracted.

Using 50% efficiency for calculation of partial mashes isn't bad insurance, though. You can measure your gravity from the partial mash, then easily adjust your DME to bring you to your target gravity. If you get better than 50%, and I've had partial mash efficiencies in the 80%+ range, you have some DME left over for a starter or the next batch.

Most crushers don't have numerical settings. You use automotive feeler guages to set the gap. Then, if you want to optimize the crush, you keep tightening the gap until you start to get slow sparges, then back off slightly. I got 75-80% on mine, out of the box, so I left it alone. If I lose efficiency as it wears, I'll adjust it.